Electrical diodes, components that allow current to flow in only one direction, are commonplace in electrical and computer systems. However, an analogue in the acoustic realm was lacking until very recently. An acoustic diode enables sound waves to travel through the diode in a first direction, but impedes sound waves front travelling in an opposite direction.
Although considerable efforts have been dedicated to demonstrating acoustic diode concepts, both theoretically and experimentally, obstacles have limited practical breakthroughs in the field. In particular, acoustic diodes that are simple to fabricate and capable of being made in small sizes have been lacking to date.